Effects of cold temperature and snowfall on stroke mortality: A case-crossover analysis

Area of Science:

• Environmental Health
• Neurology
• Epidemiology

Background:

• Investigating the independent association of cold temperature and snowfall with stroke mortality.
• Examining differential effects on hemorrhagic versus ischemic stroke subtypes.

Purpose of the Study:

• To determine if cold weather and snowfall are independent risk factors for stroke mortality.
• To assess if these environmental factors impact hemorrhagic and ischemic stroke differently.

Main Methods:

• A case-crossover study design was employed, analyzing 13,201 stroke deaths in Quebec, Canada (1981-2015).
• Weather data (minimum temperature, snowfall duration) were compared between stroke days and control days.
• Analyses were adjusted for barometric pressure and relative humidity to calculate odds ratios (OR) and 95% confidence intervals (CI).

Main Results:

• Cold temperature and snowfall were independently associated with increased odds of hemorrhagic stroke mortality in men.
• A temperature of -20°C increased hemorrhagic stroke death odds by 1.17 (95% CI 1.04-1.32) compared to 0°C.
• 12 hours of snowfall increased hemorrhagic stroke death odds by 1.12 (95% CI 1.00-1.24) compared to no snowfall; no association was found in women or for ischemic stroke.

Conclusions:

• Cold temperature and snowfall are identified as independent risk factors for fatal hemorrhagic stroke specifically in men.
• Preventive strategies for fatal hemorrhagic stroke during winter months should consider both cold exposure and snowfall in men.